A current conventional vehicle wheel alignment system uses sensors or heads that are attached to the wheels of a vehicle to measure various angles of the wheels and suspension. These angles are communicated to a host system, where they are used in the calculation of vehicle alignment angles. In the standard conventional aligner configuration, four alignment heads are attached to the wheels of a vehicle. Each sensor head comprises two horizontal or toe measurement sensors and two vertical or camber/pitch sensors. Each sensor head also contains electronics to support overall sensor data acquisition as well as communications with the aligner console, local user input, and local display for status feedback, diagnostics and calibration support. The four sensors and electronics as well as the mechanical housing that makes up each head necessarily is duplicated four times, as there is one for each wheel.
In recent years, wheels of motor vehicles have been aligned in some shops using a computer-aided, three-dimensional (3 D) machine vision alignment system. In such a system, one or more cameras view targets attached to the wheels of the vehicle, and a computer in the alignment system analyzes the images of the targets to determine wheel position and alignment of the vehicle wheels from the wheel position data. The computer typically guides an operator to properly adjust the wheels for precise alignment, based on calculations obtained from processing of the image data. A wheel alignment system or aligner of this image processing type is sometimes called a “3 D aligner.” An example of a vehicle wheel aligner using such image processing is the Visualiner 3 D or “V3D”, commercially available from John Bean Company, Conway, Ark., a division of Snap-on Incorporated.
Conventional non-vision alignment systems, with sensors mounted directly on the vehicle wheels, are becoming commodity items. The market price point for conventional systems has continued to drop due to competition and wider acceptance of image processing type, non-wheel mounted sensor, alignment systems. Main stream conventional alignment systems continue to require high accuracy and established features sets, yet lower cost technology and manufacturing processes are preferred. Unfortunately, these advances may still achieve only an incremental cost improvement. Desired are systems using wheel-mounted sensor heads of a new paradigm that reduces cost but maintains accuracy and features.